This quantity is equal to the negative gradient of electric potential. The square of this quantity, when multiplied by one half times the permittivity of a medium, gives the power associated with it. 
This quantity is equal to the negative gradient of electric potential. The square of this quantity, when multiplied by one half times the permittivity of a medium, gives the power associated with it. A Gaussian sphere can be constructed around a charged entity to find this quantity, and according to Faraday's law of induction, a change in magnetic field gives rise to it. For 10 points, identify this physical property which can be calculated by Coulomb's law.
This quantity is equal to the negative gradient of electric potential.
electric field